Isostatic presses are used in producing different types of articles, such as turbine blades for aircraft or artificial hip joints for implantation into persons. The press usually comprises a furnace provided with electric heating elements for increasing the temperature in the furnace chamber where the load, i.e. the articles, is being pressed in a loading space. After a finished pressing operation it is often important to rapidly cool the loading space so that the load therein will obtain the desired properties and so that grain growth is avoided or minimized. Furthermore, a rapid cooling results in an increased productivity, as the load may be removed rapidly, thereby reducing the cycle time. However, it is also important that an even cooling throughout the loading space is achieved.
During a high-pressure pressing operation of a high-pressure press, a pressure medium, which is accommodated in a pressure chamber of a pressure vessel, is pressurized to a very high pressure. The pressure medium is often a fluid gaseous medium, e.g. argon gas. High-pressure presses can be used in various applications, e.g. in the forming of sheet metal parts into predetermined shapes by highly pressurizing a fluid provided in a closed container. If the high-pressure press exerts an equal pressure on every side of the contents in the pressure vessel, the press is called an isostatic press. Depending on the temperature of the pressure medium during an isostatic pressing process, the process can be called a hot isostatic pressing or a HIP (hereinafter referred to as HIP), warm isostatic pressing or cold isostatic pressing.
HIP has established itself in the past decades as a competitive and proven manufacturing process for the production of components made from a wide range of metals and/or ceramics, wherein the components are used in a number of industry sectors such as the aerospace, offshore, energy and medical sector. The gas pressure acts uniformly in all directions to provide isostatic properties and a very high degree of material densification. HIP provides many benefits and has become a viable and high performance alternative to conventional processes such as forging, casting and machining. The HIP technology may be used for the compaction of metal powders (powder metallurgy HIP or PM HIP) in a container. The powder is compressed through pressure while the temperature will ensure diffusion on the contact surface between powder grains, until hollow spaces are closed so that a very high densification is achieved. The PM HIP technology is advantageous in numerous aspects, e.g. in that it is able to offer improved material properties provided by the fine and homogenous isotropic microstructure, an improved wear and corrosion resistance through extended alloying possibilities, a reduction of the number of welding operations and associated cost and inspection issues, etc.
The HIP press is often arranged in a pit or a cavity at the work site. However, there are problems related to such an arrangement, as it may be hazardous in the event of a breakage of the high-pressure press. For example, a leakage of pressure medium gas (e.g. an asphyxiating gas such as Ar) of the high-pressure press may lead to a rapid increase of the gas concentration in the pit. This may be highly dangerous for a person present in the pit for reasons of maintenance and/or inspection of the high-pressure press. Although gauges for measuring the degree of asphyxiating gases within the press and in its surroundings need be provided, as well as special training for the staff handling the presses, these and other measures may not be enough for a safe operation of the high-pressure press. Furthermore, as the pit or cavity often is relatively narrow or tight, the space is strictly limited for various high-pressure press operations such as an insertion and/or removal of a pressure vessel into and/or out from the high-pressure press. This may result in a more inconvenient operation of the high-pressure press, especially before and after pressure treatment. Furthermore, it will be appreciated that the market continuously demands larger loads and/or a more efficient HIP productivity, which leads to even larger HIP arrangements with a need for an increased efficiency. However, many prior art arrangements are not able to offer larger HIP units due to the limitations of the known arrangements.
Hence, there is a wish for an alternative arrangement which alleviates at least some of the above-mentioned problems, and which is able to provide a safer and more convenient operation.